Late last year, Mr Goodbar of eastern Arizona left his home and headed south. He was looking for a partner, and he hoped to find her in Mexico. There was just one problem: a 9-meter (30-foot) high wall of massive steel beams standing on the border between the countries.

After five days spent searching in vain for a way across the wall, he gave up and returned home.

Mr Goodbar, an endangered lobo, or Mexican gray wolf, is just one of the many wild animals affected by the expansion under the Trump administration of the US-Mexico border wall. Even before construction started on the controversial project, experts had been warning that the plans threatened upwards of 100 endangered species, with Noah Greenwald, endangered species director at the Arizona-based Center for Biological Diversity (CBD), declaring the wall “a disaster for people and wildlife alike,” which “could drive magnificent species like the jaguar and ocelot to extinction in the United States.”

Now, it seems we’re seeing those predictions play out in real-time. The ability to roam freely between the US and Mexico is “crucial to [the] long-term genetic viability” of wide-ranging species like the lobo, said biologist John Linnell in National Geographic. Back in 1977, the species had been reduced to just seven known individuals, all of whom lived in Northern Mexico – in the US, the animals had been hunted, trapped, and poisoned out of existence by the 1930s.

Thanks to captive breeding programs, the population now stands at a much healthier 200 or so, but the species’ genetic diversity is still dangerously low – which makes Mr Goodbar’s journey “an extremely important data point,” according to biologist Myles Traphagen.

“The border wall is placing the recovery of an endangered species at risk,” he told National Geographic. “And think of all the other animals [it affects], and daily events that occur that we can’t see.”

Among those other animals are endangered species like the Sonoran pronghorn, jaguars, bears, ocelots, and even bald eagles. Under normal circumstances, a project that threatened at-risk species like this would be illegal under the Endangered Species Act – but thanks to a 2017 move by the Department of Homeland Security (DHS), the border wall was made exempt from all environmental laws.

While President Biden declared upon inauguration last year that “no more American taxpayer dollars be diverted to construct a border wall,” there has been little information about any plans from the new administration to address ecological or environmental impacts from the project. Some 121 kilometers (75 miles) of planned border wall construction was canceled in Texas last year, with the DHS directing the US Customs and Border Protection to instead “begin environmental planning and actions consistent with the National Environmental Policy Act (NEPA) for previously planned border barrier system projects.”

However, the DHS has also quietly announced new construction projects across states housing the wall aimed at “[closing] small gaps” and “remediating incomplete gates.” Meanwhile, the deserts of Arizona, New Mexico, and California are strewn with an estimated half a billion dollars’ worth of steel that was delivered but never used to build the wall – half-finished building projects that environmentalists say could have “devastating impacts.”

While the US Fish and Wildlife Service states that the lobos’ recovery should not be affected by the border wall, National Geographic notes that the calculations informing that conclusion were done before the Trump administration’s construction began. With Mr Goodbar’s journey to find love canceled this year, CBD wolf advocate Michael Robinson says we are seeing concrete proof that the border wall is impacting the movement and survival of local wildlife.

“I wasn’t surprised that it happened, because we’d predicted it,” Robinson told National Geographic. “But I was bummed out.”